Make default silhouette thickness 2 on retina displays

[meng@…]

The following bug report has been submitted:
Platform:        Darwin-18.7.0-x86_64-i386-64bit
ChimeraX Version: 0.91 (2019-08-30)
Description
Silhouette edge thickness of 1 pixel is too small to see on retina displays.  Selection highlights default to thickness of 2 pixels on retina displays and silhouette edges probably should too.

Log:
UCSF ChimeraX version: 0.91 (2019-08-30)  
© 2016-2019 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open 9333 fromDatabase emdb

Opened emd_9333.map, grid size 320,320,320, pixel 1.06, shown at level 0.321,
step 2, values float32  

> set bgColor white

> set silhouettes true

> set silhouetteWidth 2




OpenGL version: 4.1 ATI-2.11.20
OpenGL renderer: AMD Radeon Pro Vega 20 OpenGL Engine
OpenGL vendor: ATI Technologies Inc.

[Tom Goddard]

Begin forwarded message:

From: Elaine Meng
Subject: Fwd: [chimerax-users] silhouette of transparent density
Date: August 30, 2019 at 9:40:42 AM PDT
To: chimera-programmers@…

...

A secondary point is that I can’t even see the silhouettes from clicking the seahorse icon in ChimeraX on this retina display until I make them fatter. I wonder if there should be any compensation of linewidth settings based on display pixels, but maybe it would be too hard to do and/or to explain.

[Tom Goddard]

Done.

Default silhouette thickness on retina displays is now 2. On non-retina displays it is 1. This matches the behavior for selection outlines.